The present invention relates to the field of injecting predetermined doses of medication without a patient seeing a needle before, during or after an injection.
The conventional syringe and needle that are used to give injections are dangerous. Over 8,000 cases of hepatitis B are caused every year by needlestick injuries in the United States. The HIV virus and hepatitis C are also often transmitted by this route.
The situation has become so severe that the United States Congress passed the Needlestick Safety and Prevention Act, which became law in November, 2000, prohibiting injections except by means of safety syringes which prevent contact with the needle after use. However injections using a safety syringe are still cumbersome and painful and the needle is exposed and dangerous before the injection is given.
AIDS, Hepatitis B and Hepatitis C are much more prevalent as result of unsafe injection practices in the developing world. It is estimated that 8-16 million cases of Hepatitis B, 2.3-4.7 million cases of Hepatitis C and 80,000-160,000 HIV infections occur each year as a direct result of unsafe injections (A. Kane, J. Lloyd, M. Zaffran, L. Simonsen, and M. Kane, Transmission of hepatitis B, hepatitis C and human immunodeficiency viruses through unsafe injections in the developing world: model-based regional estimates. Bull. World Health Org. 77, 801-807 (1999). This is a problem that urgently requires a safe and cost-effective solution.
With most drug formulations, the approved process of giving a subcutaneous or intramuscular injection with a needle and syringe involves performing the following steps, all of which require sterile technique:
1. Take the freeze-dried drug, in its rubber-capped glass vial, from the refrigerator and open the sterile cap.
2. Take a vial of sterile water for injection (WFI) from its box.
3. Remove a wide-bore needle from its sterile packaging.
4. Remove a sterile disposable syringe from its sterile packaging.
5. Attach the needle to the syringe.
6. Use the syringe to aspirate the correct volume of sterile WFI.
7. Deliver this WFI into the vial containing the freeze-dried drug.
8. Swirl or gently shake the vial, without foaming, until the drug is completely dissolved.
9. Aspirate the required dose back into the syringe.
10. Remove a narrow bore needle from its sterile packaging.
11. Replace the used wide bore needle with the fresh narrow bore needle for injection.
12. Expel all the air from the syringe and needle.
13. Carefully swab the skin over the injection site with disinfectant.
14. Insert the needle to the correct depth and location with minimal pain.
15. Inject the drug and withdraw the needle.
16. Permanently dispose of the needles and syringe to prevent needlestick injury to the operator or third parties.
These techniques must be taught to health care professionals. This is not a suitable process for the untrained layman.
The World Health Organization has estimated that it will need to deliver 3.6 billion injections per year by 2005 and that it will not be able to access the medically trained staff to achieve this goal. This old fashioned technology has therefore been deemed by the World Health Organization (WHO) to be incompatible with their requirements for planned Global Program of Vaccination and Immunization (GPV) initiatives. The WHO has formally called for a program of research and development to develop radical new technology for vaccine delivery. (L. Jodar, T. Aguado, J. Lloyd, and P-H Lambert (1998), Revolutionizing Immunizations, Gen. Eng. News 18 (P. 6).
The functional criteria required by the WHO are:
Injection device and vaccine dose packaged together;
Safe disposal of contaminated needles and other material;
Zero risk of cross infection;
No waste;
No pain; and
Affordable.
Another hazard of syringes is their re-use; often after inadequate washing and sterilizing, especially in the developing world. These re-used syringes have also caused serious outbreaks of infection. This problem requires xe2x80x9cself-destructxe2x80x9d or xe2x80x9csingle-usexe2x80x9d syringes that automatically disable themselves after their first use.
The industry has addressed these challenges by a complete redesign of the needle and syringe to incorporate automatic or semi-automatic covering of the needle after use (U.S. Pat. No. 5,980,488) or retraction of the needle by rubber bands, springs or vacuum into the body of the syringe (U.S. Pat. Nos. 5,782,804; 6,015,438; 6,050,977) or modifications that destroy the functionality of the syringe mechanism after one use (Becton Dickinson xe2x80x9cSoloshot(trademark)xe2x80x9d syringes). These so-called safety syringes are inevitably much more expensive than the standard syringe which retails at around $0.03-0.07 per unit. Many of the new safety syringes cost $0.50 to $1.00 each. These devices are not yet universally used in mass vaccination campaigns because the increase in expense cannot be supported by the agencies involved.
An inexpensive, single-use, self-destruct, pre-filled device recently introduced is the xe2x80x9cUniject(trademark)xe2x80x9d made by Becton Dickinson and Company. This plastic blister with attached needle is certainly cheap but it still requires training and skill to use and has a dangerous exposed needle, which can cause needlestick injury both before and after the injection.
A series of novel solutions to these problems in the form of a family of disposable injector devices that operate on principles different from the standard syringe and needle is described in U.S. Pat. No. 6,102,896. Essentially these devices, along with most others that have been described, involve redesigns of the technology of injection to eliminate the hazards and simplify the skills needed so that training is no longer required.
Some of the devices described in the ""896 patent actually incorporate similar principles to the conventional syringe and hollow metal needle as well as features to simplify and automate the steps of injection. This approach will only be successful if the new devices can demonstrate the remarkable durability and robustness of design that has enabled the syringe and needle to totally dominate the field for over 150 years without any fundamental changes.
Additionally, some of the elements of design in the devices described in ""896 patent require very precise manufacturing and quality control to ensure that a sequence of steps required for their operation proceed in the required order. These considerations make these devices less than ideal. A more attractive solution would be a robust and easily manufactured device that has the elegant simplicity of the syringe and needle plus the benefits of automation and safety now required by law.
A novel approach is to actually retain the existing well-proven devices such as the syringe and needle or the Uniject(trademark) as the core drug delivery device but to add to them a simple mechanism that provides the manipulations required to deliver a correct injection and also incorporates the safety modifications that are needed to prevent needlestick injury and ensure self destruct capability. A surprisingly simple and cheap modification to a sterile package for the standard syringe and needle can successfully be used to automate the medical skills needed to deliver a safe injection and dispose of the hazardous needle afterwards. The sterile package consists of a housing for the syringe barrel, which can telescope into a larger diameter hollow cap covering the syringe plunger. The syringe and needle are located fully inside this two-part packaging sheath, which completely encloses and protects them.
Accordingly, it is an object of the present invention to provide an injection of a predetermined dose of medication without a patient seeing a needle before, during or after an injection.
It is another object of the present invention to provide a sterile package consisting of a housing for a syringe barrel, which can telescope into a larger diameter hollow cap covering a syringe plunger with a syringe and needle located fully inside the syringe barrel and hollow cap to completely enclose the syringe after use.
It is yet another object of the present invention to provide two plastic injection molding parts and a spring which are used in combination with a pre-filled syringe to inject an individual and completely conceal a used syringe.
It is still yet another object of the present invention to use a pre-filled blister-type injection device for injection of a predetermined amount of medication and have the injection needle sealed between a barrel and a cap for safe disposal.
These and other objects of the invention, as well as many of the intended advantages thereof, will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.